Filter device and parts thereof and a method for operation of the filter device

ABSTRACT

The invention relates to a filter device having a filter housing part ( 10 ) which comprises a filter element ( 12 ) and which can be detachably connected to the other filter housing part ( 20 ). Because there is a valve means ( 24 ) which clears a fluid path in the interconnected state of the housing parts ( 10, 20 ) and in the separated state of the housing parts ( 10, 20 ) from one another at least partially blocks it, instead of known quarter-turn fastener and stopper solutions a blocking means is devised which can be economically implemented and which requires decidedly less installation space. The invention relates also to a process for operation of a filter device.

The invention relates to a filter device having a filter housing part which comprises a filter element and which can be detachably connected to the other filter housing part. The invention furthermore relates to certain parts of the filter device and a method for its operation.

The prior art relative to these filter devices includes among others so-called spin-on filters, in the respective filter housing part of which a filter element designed especially for the respective filtration task is integrated. If the filter element is clogged with dirt and consequently the filter device has become unusable for its filtration task, the entire filter device, that is, the filter housing in addition to the filter element, must be replaced by a new filter device. This has the disadvantage that the entire unit must be disposed of, although in itself the actual filter housing part would still be usable. To remedy this, it has already been proposed that in the pertinent spin-on filter only the used filter element be replaced and the filter housing part with a new filter element be used as a newly assembled filter device, especially for removing dirt from hydraulic circuits. But here fundamentally the problems arises that operators or even specially trained maintenance personnel forget to use a new filter element and that then the re-connected filter housing part which is designed as a screw-in cartridge, even without the filter element enables operation of the hydraulic system, but without dirt in the fluid flow being removed, with the result that serious damage to the entire hydraulic system can occur. Comparable problems also arise for other fluid media such as gases or pasty media.

In order to be able to establish greater operating reliability in this respect, DE 10 2004 014 149 A1 discloses a quarter-turn fastener as a fastening means by which the filter housing can be detachably mounted on the fluid means of the hydraulic circuit, by the rotary motion of the filter housing when the quarter-turn fastener is released and locked a blocking part being controllable which blocks and clears the pertinent fluid connection, so that in this way the filter can be reliably changed. A comparably designed solution is also shown in DE 10 2004 008 879 A1 which instead of the quarter-turn fastener has a stopper solution with a plate-shaped slide part for blocking and clearing the fluid connections. These solutions are very reliable in operation; both the quarter-turn fastener and also the stopper solution however require a relatively large amount of installation space and thus engender the corresponding production costs.

On the basis of this prior art, the object of the invention is to further improve the known solutions such that at low production costs and reduced installation space a blocking solution is devised which ensures that the filter device can only ever be operated together with its associated filter element, even when the pertinent filter element is replaced by a new, unused element. This object is achieved by a filter device with the features of claim 1 in its entirety.

In that, as specified in the characterizing part of claim 1, the blocking solution is a valve means which in the interconnected state of the housing parts clears a fluid path and in the separated state of the housing parts from one another at least partially blocks it, a blocking means which can be economically implemented and which requires considerably less installation space is devised instead of the described quarter-turn fastener and stopper solutions.

If the fluid flow through the filter device is completely stopped by the valve means, the hydraulic control unit evaluates this as a problem, with the result that an error report is delivered from which the operating or maintenance personal can then detect the absence of the filter element or by choking the fluid volumetric flow the respective hydraulic function is maintained; however, the differential pressure on the filter device increases such that a correspondingly mounted fouling display responds when the element is absent and delivers the message “Fouled filter element to be replaced” with the result that for this purpose the filter device is checked with respect to its serviceability and the possible absence of the filter element can be established without failure of the hydraulic components of the system occurring. Operators experienced in the handling of hydraulic machinery will moreover be able to recognize even without the display that the filter element is missing when the corresponding noise or slackening machine performance occurs due to the described choking of the volumetric flow.

In one preferred embodiment of the filter device as claimed in the invention, the valve means has a valve element which can be actuated via a trigger part of at least one of the two filter housing parts and/or of the filter element, and especially in the connected state of the housing parts opens the valve element and in their state separated from one another at least partially closes it. In addition to the already described opening and closing function with possible choking of the volumetric fluid flow, via the indicated trigger part forced actuation of the valve element of the valve means is ensured, so that in this respect malfunctions are precluded. Preferably the trigger part is a component of the interchangeable filter element and the valve element is a component of the other filter housing part.

In another especially preferred embodiment of the filter device as claimed in the invention, the valve element consists of at least one valve component which in the closed state of the valve element forms a fluid-tight membrane surface or borders fluid-choking passage points within the membrane surface, and which in the opened state essentially enables free fluid passage from one filter housing part with the filter element inserted via it in the direction of the other housing part and vice versa. Based on the possible reversible fluid direction it is possible, with the valve means actuated, to induce a backflushing process for the filter element in order to remove dirt from it in counterflow. The configuration of the valve element in the shape of a membrane makes it possible to still further reduce the required installation space.

The respective valve component preferably consists of a type of spiral arm with spring-elastic properties, and at least one of the spiral arms can end in a fixing ring which, designed as a locking or snap ring, then enables fixing of the valve means in one of the filter housing parts with simple handling.

The invention furthermore relates to a valve means for the pertinent filter device according to the configuration of features of claim 8 and a specially designed filter element with a trigger part according to the configuration of features of claim 9. The invention furthermore relates to a method according to the configuration of features of claim 10 in which a fouling display based on the differential pressure is connected between a supply and discharge for fluid in the filter housing in such a way that in the absence of the filter element the valve means chokes the fluid flow in order to maintain the function of the hydraulic circuit. The invention furthermore relates to a method according to the configuration of features of claim 11 which calls for the control means of the hydraulic circuit to deliver an error report and/or to turn off the hydraulic circuit in the absence of a filter element and with the valve means closed.

The filter device as claimed in the invention will be detailed below using one embodiment. The figures are schematic and not to scale.

FIG. 1 shows a front view of a longitudinal section of the head-side part of the filter device as claimed in the invention;

FIG. 2 shows the filter element which can be inserted into the filter device as shown in FIG. 1 with a trigger part in a perspective top view;

FIG. 3 shows a perspective top view of the trigger part as shown in FIGS. 1 and 2;

FIGS. 4 to 7 show in a perspective top view different embodiments of insertable valve means, FIG. 6 showing the opened operating state of the valve means as shown in FIG. 5.

The filter device as shown in FIG. 1 has a cup-shaped filter housing part 10 which surrounds the filter element 12, as is shown for example in FIG. 2. Flow takes place through the filter element 12 from the outside to the inside viewed in the direction of looking at FIG. 1 and the filter element has a conventional filter element structure which is not detailed, for example consisting of a pleated, multilayer filter mat which is supported against a fluid-permeable support pipe. In this connection, fouled fluid is optionally supplied from a hydraulic circuit which is not detailed via the fluid supply 14 to the filter device, and cleaned, filtered fluid travels via a center channel 16 of the filter element 12 to the fluid discharge 18 of the filter device. In order to be able to backflush the filter element 12, it would also be conceivable to operate the filter device in the reverse fluid direction; likewise it would be possible in a specially designed filter element 12 to reverse the direction of fluid throughflow so that then the fluid to be cleaned flows through the filter element 12 from the inside to the outside. In these instances then, generally to support the pleated filter material, a support pipe or other support element such as a grating must be attached on the outer peripheral side. This structure of a filter device is conventional so that it will not be detailed here. It is likewise conventional for the other filter housing part 20 which forms a type of filter head to have a supply 14 and a discharge 18 and to extend over the filter housing part 10 on its upper free end on the front and to be detachably connected to the filter housing part 10 via a screw-on section 22.

The filter device furthermore has a valve means 24 as shown in FIG. 4. Other solutions for the valve means 24 are shown in FIGS. 5 to 7. If, as shown in FIG. 1, the two housing parts 10, 20 are connected to one another, the valve means 24 is moved into the open position which clears the fluid-carrying path, and in the separated state of the housing parts 10, 20 from one another the pertinent fluid-carrying path between the center channel 16 and the fluid discharge 18 is blocked. In the absence of a control part and designed as a complete closure (valve function) the valve means remains closed until the pressure p1 has reached or exceeded the opening pressure P0 of the valve means, i.e., p₁<p₀:p₂=0 for an unpressurized connection to the tank, volumetric flow Q=0, p₁>=p₀:p₂=p₁·Δp_(valve), ideally for Δp_(valve)=0:p₂=p₁.

In the absence of the control part and designed as a choke (spiral disk with passages) a pressure drop will take place over the component so that p₁>p₂. The resulting pressure difference Δp_(valve) is used to trigger a signal of an optionally connected fouling display.

As shown in greater detail in FIG. 4, the valve means 24 has a valve element 26 which can be actuated via a trigger part 28, as is detailed in FIG. 3. In this case the trigger part as shown in FIGS. 1 and 2 is a component of the filter element 12, and as a result of its conically tapering control parts on its free front end in the form of opposing bridge surfaces is able to push against the closed valve disk as shown in FIG. 4, into an open spiral configuration, as shown in FIG. 1. If the two filter housing parts 10, 20 are separated from one another by unscrewing over the screw-on section 22, the trigger part 28 disengages from the valve means 24, and the valve element 26 assumes its largely closed position in the form of a flat membrane surface as shown in FIG. 4.

Since the valve component of the valve element 26 in the embodiments as shown in FIGS. 1 and 4 is consequently formed from a spiral arm 32 with spring-elastic properties, this process of pushing can be repeated as often as desired for an opening process and spring-elastic resetting for closing the valve means 24 so that in this way a very large number of changing processes for new filter elements 12 is possible if, when fouled, they are to be replaced accordingly by new filter elements. Since the valve means 24 can be fixed interchangeably in the upper filter housing part 20, for a possible failure of the spiral arm 32, replacement of the valve element 26 is also possible. This interchangeability is however not absolutely necessary. The spiral arm 32 which can be obtained from a flat metal plate can be obtained by means of conventional cutting technology, also including laser cutting, water jet cutting, etc. A correspondingly wound wire with round or rectangular cross section could likewise be used.

The metal base plate as the base material, preferably made in circle form, itself need not be spring-elastic, and the resetting moment for closing the valve means 24 can likewise arise exclusively by the raising of the spiral arm 32 in helical form by the trigger part. The raising plug 34 which tapers to the outside (compare enlargement as shown in FIG. 3) in terms of its outside contour is matched to the spiral line of the raising arm so that in this way the spiral arm 32 undergoes guidance both for the pushing process and also for the resetting process which in this respect ensure especially careful actuation of the valve element 26. Fundamentally however a cylindrical raising pin (not shown) could assume the function of the conical raising plug 34.

The trigger part 28 is shown as an individual component in FIG. 3 for better illustration. The trigger part 28 on the bottom side has a contact-making plate 36 which can be moved into the top end of the filter element 12 until the free end of the filter element 12 comes into contact with the encompassing edge 38. This encompassing edge 38 on the outer peripheral side has an engagement groove 40 which is interrupted by engagement points 42 which point down, which are preferably diametrically opposite one another, and which ensure that by way of a corresponding catch or lock connection the annular trigger part 28 is detachably fixed with a corresponding strip-like or cam-like engagement part 44 on the inside of the cup-shaped filter housing part 10 (compare FIG. 1). A cylindrical center plug 48 is located on the top of the contact-making plate 36 by way of individual stiffening bridges 46 and is permanently connected to the contact-making plate 36 and to the encompassing edge 38, the individual stiffening bridges 46 extending radially to the outside away from the longitudinal axis 50.

The top of the center plug 48 is connected to the aforementioned raising plug 34, the three inserted control parts 30 extending between an annular flange 52, on the top end of the center plug 48, and a contact-making and pushing pin 54 on the free end of the trigger part 28. These bridge-like trigger parts 30 can be further stiffened by at least one middle ring 56. The fluid passages 58, bordered by the stiffening bridges 46, and the top of the contact-making plate 36 and the bottom of the encompassing edge 38 are used for incident flow onto the actual filter element with its filter medium in the seated state. The fluid passages 58 more or less form the inflow channel between the filter element and the optional “dirt catcher” which is shown here and which is used to catch dirt in the direction of flow through from the outside to the inside. The insertion bevels 60 which point down on the stiffening bridges 46 facilitate insertion of the trigger part 28 into the (optional) dirt catcher along its upper edge. This trigger part 28 consists preferably of a plastic material which can be economically produced for example by means of an injection molding process. For permanent connection of the trigger part 28 which is made in one piece to the filter material of the filter element 12 there can be a cement connection which is not detailed. Instead of three control parts 30, there can also be a different number of control parts (not shown).

The filter element 12 with the trigger part 28 forms a type of manageable function unit which can be completely replaced as a replacement part and thrown away. But it is possible to reuse or recycle the plastic trigger part 28. It is still within the scope of the invention, in an embodiment which is not shown, to assign the trigger part 28 to the other filter housing part 20 and to provide the valve means 24 on the filter element 12 accordingly.

If, as shown in FIG. 4, the valve element 26 of the valve means 24 forms an essentially closed membrane surface, when the filter element is replaced and insertion of a new filter element 12 is forgotten, the valve means 24 cannot be pushed by the trigger part 28 of the filter element 12 as shown in FIG. 1 into its open position, but remains in the closed valve function with the result that a reporting or control means would immediately relay an error report to the operator to indicate that the filter element 12 to be inserted for reliable operation of the system is lacking. In this way dirt damage caused by lack of filtration within the hydraulic circuit can be reliably avoided. Another approach for a functional valve means 24 is given by the embodiment as shown in FIGS. 5 and 6. There, in the closed position as shown in FIG. 5, between the parts of the spiral arm 32 there is a choking passage site 62 which both in the opened position of the spiral spring valve as shown in FIG. 6 and also in its closed state as shown in FIG. 5 enables a choked fluid flow coming from the middle channel 16 in the direction of the fluid discharge 18. Due to this fluid passage point, the hydraulic function can be further maintained; a fouling indicator which is not detailed and which operates based on pressure difference detection would however be able, in the absence of the filter element 12 and accordingly with the closed spiral spring valve configuration as shown in FIG. 5, to signal the pertinent system state as fouling in order to compel filter element replacement in which it is then established that the element 12 is not in its place in the housing part 10.

These pressure difference-controlled fouling displays are easily commercially available in a plurality of versions, and when a working new filter element has been inserted, the pressure difference to be detected between the fluid supply 14 and the fluid drain 18 in the ideal case is near 0. As fouling increases, the pressure difference value then increases until the fouling indicator suggests replacement of the used filter element 12. A comparable pressure difference situation arises when the helical spring valve as shown in FIG. 5 remains closed without the filter element 12 inserted and choked fluid flow takes place only by way of the passage point 62. As a result of the spring elastic configuration of the respective spiral arm 32 it is moreover ensured that on the top of the filter element 12 a type of adjustment force is applied which presses the respective filter element 12 in the direction of the bottom part of the filter housing part 10; this likewise contributes to an increase of operating reliability.

The other embodiment of the valve element 26 shown in FIG. 7 for the valve means 24 has the particularity that in addition to the spiral arm 32, a fixing ring 64 is molded on in one piece to the outside and has two continuous points of application 66 for an actuating tool which is not detailed, designed as spreading pliers with which it is possible to again detachably fix the valve element 26 as a snap ring in an assignable engagement groove 68 (compare FIG. 1) in the head-side filter housing part 20. In this configuration as shown in FIG. 7, the valve element 26 in turn in the middle has an engagement opening 70 for possible passage of the contact-making and pushing pin 54 (compare FIG. 3).

Another desirable side effect in the described configuration of the filter device is that a type of key port system is achieved, i.e., for obtaining a serviceable filter device for a hydraulic circuit it is necessary for the filter element 12 to have the indicated trigger solution 28; otherwise malfunctions on the hydraulic system occur. Since fundamentally knockoffs are being found to an increased degree in the replacement parts business and are often of lower quality, which the user cannot easily detect, it is possible in this way for only original filter elements with the trigger part 28 and the fluid housing to be used with special valve technology. Cheap single elements conversely cannot be serviceably used. The bridges 30 with the center ring 56 of the trigger part moreover form a type of capture structure which keeps small parts such as screws, nuts or the like from falling into the interior of the filter element 12. 

1. Filter device having a filter housing part (10) which comprises a filter element (12) and which can be detachably connected to the other filter housing part (20), characterized in that there is a valve means (24) which in the interconnected state of the housing parts (10, 20) clears a fluid path and in the separated state of the housing parts (10, 20) from one another at least partially blocks it.
 2. The filter device as claimed in claim 1, wherein the valve means (24) has a valve element (26) which can be actuated via a trigger part (28) of at least one of the two filter housing parts (10, 20) and/or of the filter element (I 2), especially in the connected state of the housing parts (10,20) opens the valve element (26) and in their state separated from one another at least partially closes it.
 3. The filter device as claimed in claim 2, wherein the trigger part (28) is a component of the interchangeable filter element (I 2) and the valve element (26) is a component of the other filter housing part (20).
 4. The filter device as claimed in claim 2 or 3, wherein the valve element (26) consists of at least one valve component which in the closed state of the valve element (26) forms a fluid-tight membrane surface, or borders fluid-choking passage points within the membrane surface, and which in the opened state essentially enables fluid passage from one filter housing part (10) with the filter element (12) inserted, via it in the direction of the other housing part (20) and vice versa.
 5. The filter device as claimed in claim 4, wherein the respective valve component is formed from a type of spiral arm (32) with spring-elastic properties.
 6. The filter device as claimed in claim 5, wherein at least one of the spiral arms (32) undergoes transition into a fixing ring (64), especially of the snap ring type, with which the valve element (26) can be fixed on the other filter housing part (20).
 7. The filter device as claimed in one of claims 1 to 6, wherein one filter housing part (10) forms a filter cup for holding the filter element (12) and the other filter housing part (20) forms the filter head with the fluid connections, especially in the form of a supply (14) and discharge (18).
 8. Valve means (24) for a filter device as claimed in one of claims 1 to 7, wherein it has a valve element (26) with at least one valve component in the form of a spiral arm (32).
 9. The filter element (12) for a filter device as claimed in one of claims 1 to 7, wherein the filter element (12) has a trigger part (28) for the valve means (24).
 10. Method for operation for a filter device as claimed in one of claims 1 to 9, wherein a fouling indicator based on the differential pressure is connected between the supply (14) and the discharge (18) for fluid in the filter housing such that in the absence of the filter element (12) the valve means (24) chokes the fluid flow to maintain the function of the hydraulic circuit and to lead to a fouling display without tolerances.
 11. The method for operation for a filter device as claimed in one of claims 1 to 9, wherein in the absence of a filter element (12) and with the valve means (24) closed, a control means of the hydraulic circuit delivers an error report and/or turns off the hydraulic circuit. 